1. Field of the Invention
The present invention relates to telecommunication networks, and more specifically to a method and apparatus for setting up virtual circuits quickly when using signaling protocols.
2. Related Art
Virtual circuits are often provisioned between network devices. A virtual circuit generally defines a path (including intermediate devices and transmission paths) traversed by data packets from one network device to the other. The network devices at either end of the virtual circuit are generally referred to as end systems.
Signaling protocols are often used to perform various control tasks (set up, release, notify, etc.) in relation to virtual circuits as is well known in the relevant arts. For example, ITU-T recommendation Q.2931 and UNI Signaling Specification together provides a specification using which switched virtual circuits (SVCs) may be controlled in asynchronous transfer mode (ATM) based networks, as is well known in the relevant arts.
Q.2931 is described in further detail in a document entitled, “B_ISDN application protocols for access signaling Broadband Integrated Services Digital Network (B-ISDN)—Digital Subscriber Signaling System No. 2 (DSS 2)—User_Network Interface (UNI) layer 3 specification for basic call/connection control”, (hereafter “Q-2931 Standard Document”). UNI 4.0 Standard is described in further detail in a document entitled, “ATM User_Network Interface (UNI) Signaling Specification, Version 4.0”, AF_SIG—0061.000, (hereafter “UNI 4.0 Specification”) Available from www.atmforum.com. Both the documents are incorporated in their entirety herewith.
Signaling protocols generally define a format for the control messages, which can be used by a network device to perform (and cause other devices to perform) the corresponding control task associated with a virtual circuit. For example, a network device may send a setup message to cause a virtual circuit to be set up, and send a release message to cause the virtual circuit to be terminated.
It may be desirable to process control messages efficiently while minimizing various types of overhead such as bandwidth and/or processing requirements. For example, it may be desirable to set up a virtual circuit quickly at least in some environments. As an illustration, when voice calls are set up using a packet switched network (e.g., using voice over IP network supported by ATM backbone), a virtual circuit may be set up to support a newly initiated voice call.
In such a situation, it may be desirable to complete set up of virtual circuits quickly such that the voice connection is provided quickly. The ability to set up the virtual circuit may be particularly more important when many virtual circuits need to be set up in a fairly short duration.